Apparatus for reduction



Sept. 30, 1941. R. s. BUTLER APPARATUS FOR REDUCTION Original Filed Oct.19, 1935 3 SheetsSheet 1 Sept. 30, 1941. R. s. BUTLER APPARATUS FORREDUCTION Original Filed Oct. 19, 1955 I5 Sheets-Sheet 2 r 0 6 w A v nfi I M a H 3 5 M l w .J y 0 O M 0 0 5 i f 4 v m a %/5 4 9 I s m 5 n u 2m a n w .w a r? 2 5 g i m 2 a, y 3 l- I I i I l 0 l. w 2 Z 6 jioier )6.BazZer jittorne gps R. S. BUTLER APPARATUS FOR REDUCTION Sept. 30, 1941Original Filed Oct. 19, 1935 5 Sheets-Sheet 5 Invenfor 23056215 )5.ZazZer Reissued Sept. 30, 1941 UNITED STATES PATENT OFFICE SullivanMachinery Company, a corporation of Massachusetts Original No.2,168,082, dated August 1, 1939, Serial No. 45,796, October 19, 1935.

Application for reissue June 30, 1941, Serial No. 400,573

36 Claims. (01. 83-9) This is an application for reissue of LettersPatent No. 2,168,082, granted August 1, 1939.

. vention are an increase in efficiency of reduction and a minimum useof power, a negligible use of power when the machine is running empty,and a continuous automatic feed whereby the mass undergoing reductionserves to control the admission of new particles to the zone ofreduction to take the place of the reduced particles which escapetherefrom. Another purpose is the provision of an apparatus in which theload undergoing reduction is, during the reducing cycle, subiected tosubstantially constant reducing stress or pressure. As an example, Ioscillate or reciprocate a compact load of particles through a definedreducing zone, such zone being defined by an oscillated reductionchamber and including the space within the interior of the chamber atany instant and all the other space within the interior of the chamberin the various positions of the latter as it is moved in the course ofits oscillation, and subject the load not merely to longitudinalreducing pressure at each change of direction of movement, but subjectit to transverse reducing pressure intermediate said changes ofmovement. Another purpose is the provision of an improved reductionmachine in which a reducing chamber and a feed passage thereto areunitarily oscillated or reciprocated, during the maintenance of aconstant supply of new particles for reduction as the reduced particlesescape from the device. Another purpose is the provision of improvedfeeding means for an oscillating reduction mill.

Other objects will appear from time to time in the course of thespecification and claims.

The present application includes material divided from applications Nos.759,902, filed on December 31, 1934, and 37,804, filed on August 26,1935, copending with application Ser. No. 45,796, filed on October 19,1935, which matured into Patent No. 2,168,082.

I illustrate my invention more or less diagrammatically in theaccompanying drawings, where- 111-- Figure 1 is a horizontal section onthe line i-J: of Figure 2;

Figure 2 is a vertical section on the line 1-2 of Figure l;

Figure 3 is a section on the line 3-3 of Figure Figure 4 is a section onthe line H, indicated in both Figures 2'and 3;

Figure 5 is a section corresponding to the section taken along the line3-3 of Figure 1, with the material undergoing reduction and the reducingcharge included, in order to indicate movement of the material in thecourse of the reducing method herein described;

Figure 6 is a vertical, radial section through a reducing chamber,showing the chamber empty except for a reducing charge;

Figure 7 is a similar section, illustrating the reducing chamber at theend of its travel toward the right, with the load moving toward theright Just prior to the impact caused by the engagement of the load withthe right end of the chamber;

Figure 8 is a similar view after the reducing chamber has reversed itsdirection and is moving toward the left, carrying the charge with it;

Figure 9 illustrates the reduction chamber moving toward the left, afterits velocity has begun to decrease, and with the load moving away fromthe right end of the chamber and toward the left.

Figures 10, 11 and 12 are fragmentary sectional views showingmodifications in chamber structure.

Like parts are indicated by like symbols throughout the specificationand drawings.

Referring to the drawings, Figures 1 to 4 illustrate my improvedreducing mill, and Figures 5 to 9 inclusive are primarily directed toillustrating the mode of operation or crushing method of the mill.Figures 10, 11 and 12 illustrate modifications.

Referring to the drawings, and considering first the movement of thematerial through my reduction mill, I illustrate, as at A in Figure 5, amass of material awaiting crushing, which may be supplied in anysuitable fashion to the hopper I. It escapes thence along any suitablefixed chute 2, the material passing down this fixed chute or spout beingindicated at B in Figure 5. This fixed spout 2 may be mounted in anysuitable fashion in relation to the housing generally indicated as l,which housing is mounted upon any suitable base 4 and is shown as havinga circumferential cylindrical wall I, an end wall or gate 8, and anopposite solid end wall 1, formed with the bearing supporting sleeve 8which receives 0 anti-frictional bearings 9 for the shaft III to whichincludes the outwardly extending yoke or supports l2. Formed integrallytherewith is the feed receiving sleeve or stirrup I3 which surrounds butis spaced outwardly from the tapered sleeve II which is keyed to and islocked against the tapered shaft portion H, as by the key ll, washer l6and nut ll upon the screw-threaded extension I! of the shaft 10.

Secured in any suitable fashion to the supports i2 is the reduction orreducing chamber proper, generally indicated as 2ll, which includes anouter arcuate wall 2| provided with apertures 21, an inner annular wall23, and thickened and wall 2|. The annular walls 2| and 23 are here inshown as concentric with the shaft II, the common center being indicatedat X in Figures to 9 inclusive.

The inner or upper wall 23 of the reduction chamber is provided withfeed apertures 25 at the outer end of a feed passage which is bounded ontwo sides by walls 28. The feed passage so formed communicates at itslower end directly with the reducing chamber 20 through the apertures 25and at its upper end directly with the space between the sleeves l3 andI4 through an opening 21. It will be seen, as in Figures 3 and 5, thatthe outer sleeve I3 is open at its upper side, as at 30, this openingbeing masked by the arcuate shield or saddle 3| associated with thelower end of the feed spout 2. The outer sleeve I! at its lower side hasthe opening 21 communieating through the feed passage with the apertures25. It will be clear, as from Figure 5, that the mass of feed material13 is in communication with, and rests upon the mass of feed material Cwithin the sleeve II. This in turn rests upon the mass of feed materialD in the feed passage defined by the walls 28. By reason of the sweepingof the upper surface of material C, as the reduction chamber swings,back and forth beneath the lower end of the column of material 8, therewill be a size-reducing operation efiected.

The load in the reduction chamber 20 is generally indicated as at E inFigures 5, '1, 8 and 9. The charge of reducing media, shown asstratifled or classified, for reasons which will later appear, includesballs or particles of maximum size G, particles of intermediate size G-iand particles of minimum size GI. These have associated with them, andwork against, particles undergoing crushing of maximum size H,intermediate size H----! and minimum size H2. The fully reducedparticles escape through the apertures 22 in the lower or outerreduction chamber wall 2| and are indicated as at I, falling within thehousing 5 and into the discharge hopper I5 which communicates with anysuitable discharge spout or chute 3B.

In the employment of the mill I impart a rotary oscillation to thereducing chamber Iii about the axis X of the shaft 10. This movementmight be imparted to the reduction chamber in a variety of ways but Iillustrate means for obtaining this oscillation, for example in Figures1 to 4.

40 indicates a drive shaft which is keyed to the drive pulley ll, aboutwhich may pass any suitable belt, to a power source not herein shown.The shaft 40 may be supported for example in anti-frictional bearings 42and 43. The bearings I! are mounted on any suitable support 44, securedto the base I. The bearings 48 are mounted in a sleeve 5, herein shownas formed integrally with a closure plate 48 secured in any suitablemanner to the generally vertical housing wall 41 in which, also, theshaft II is rotatab r mounted as by the hearings to. The oposite side ofthe housing so formed is closed, as by the wall I of the reductionchamber housing 5, which wall extends outwardly as at 4' and isconnected to the wall 41 as by any suitable side and end wall structure4!.

Positioned within the housing so formed, and formed integrally with theend of the shaft 40, is a disc 5! to which is adiustably secured, forrotary adjustment, an inner inset disc 5|. Outwardly projecting fromthis inset is the eccentric stud 52 surrounded by the anti-frictionalbearings I! which in turn are surrounded by the eye 55 of an oscillatingarm or connecting rod II. This arm is pivoted at its outer end as at 58to a crank arm 51 secured to the shaft Ill. It will therefore beunderstood that when the shaft 40 is rotated in response to any suitabledriving connection, the discs 50 and El rotate and move the stud 52through a circular path. This circular movement is converted, by meansof the connecting rod 54 and arm 51, to a rotary oscillation of theshaft III. This oscillation is in turn imparted to the reduction chamber20, the feed passage extending thereto and the sleeve l 3. The slidingconnection between the sleeve l3 and the shield ll maintains acontinuous and uninterrupted connection with the mass of material A andB sliding from the hopper i down through the feed spout 2. Thus thereduction chamber may be continually oscillated without in any degreeinterrupting the feed of material thereto.

It willbe realized that whereas I have described and shown a practicaland operative device. nevertheless many changes may be made in the size,shape, number and disposition of parts without departing from the spiritof my invention. I therefore wish my description and drawings to betaken as in a. broad sense illustrative and diagrammatic rather thanlimiting me to my precis showing.

The use and operation of my invention are as follows:

The broad outline of my invention, and the operation of my reductionmill, will readily be understood. for example in connection with Figures5 to 9. The material to be reduced is fed from a hopper I, through afixed feed spout 2, to and through an oscillated sleeve i3, which inturn communicates with the oscillated feed passage bounded by the walls25. From this passage the material passes directly to the reductionchamber 20.

The material through the entire line of feed follows a continuous path.The feed material A, B, in the fixed feed hopper and spout I, 2, restsupon the material C in the oscillated sleeve it which is continuous withthe mass D in the oscillated feed passage. This entire line or column offeed rests upon the top of the load E, and the load serves as the meansfor regulating the feed of new particles to take the place oi. theparticles undergoing crushing, because the load, as is clear, forexample from Figure 5, masks or underlies the bottom of the feed passagebounded by the walls II.

In order to make the operation and characteristics of my mill clear, Iwill outline briefly, under various heads, the most importantcharacteristics.

Reciprocating a load of media and material.- The oscillation orreciprocation of the reducing chamber 20 reciprocates a load whichincludes the particles to be reduced and particles of reducing media.The particles or balls of reducing media, G, G-l, G2, are scatteredthrough the mass E of particles undergoing reduction, as shown in Figure5. As the chamber "changes its direction of rotation, its right hand end24 receives the impact of the load, and causes the load also to changeits direction of movement. In Figure 7 the load is about to engage withthe right hand end 24 of the chamber 20. In Figure 8 the load is beingmoved toward the left with the chamber. In Figure 9 the chamber hasbegun to slow down and the load is still moving to the left. It willcontinue to move to the left until it engages the left end 24 of thechamber. This engagement will force the load to move to the right, andthis cycle of movement of the load continues as long as sufl'lcient newparticles are added to the load to maintain the process. The reducedparticles I escape through the apertures 22 of the wall 2| and may passfrom the hopper I and the discharge spout 38.

Load conflnement.-The chamber 20, at its various positions in the courseof its oscillation, defines a reduction zone which includes the interiorof the chamber at all normal positions of the chamber. In this reductionzone an intermittent centrifugal thrust is maintained downwardly towardthe bottom of the zone. The material travels from end to end of the zonewith a periodic change in the direction of movement caused by theoscillation of the reduction chamber 20. The interior of the chamberproper may be described as a zone of restriction, which is moved throughand contained in the larger reduction zone. The load as a whole isconfined in close association with the walls of the chamber 20. It isessential for maximum efilciency, that the general motion of both thereducing media and the material undergoing reduction be confined to apath which conforms generally to the path of the load as a whole, thatthe particles undergoing reduction may be held in contact with theparticles of the reducing medium. Wandering of the load or freedom ofmovement is destructive of efliciency and is prevented by maintainingthe load as a relatively compact mass. The cross-section of the chamber20 along the path of movement of the load is therefore desirably, forsome purposes, uniform, and the crosssectional area at least should be.so far as practicable, maintained substantially uniform. Since in thepractice of the invention uneven wear of at least the outer chamber wall2| may be anticipated, it will be appreciated that maintenance of anapproximation of uniformity of cross-section and of cross-sectional areais all that can be expected. With the maintenance of crosssectional areaapproximately uniform, the only displacements of the bounding surface ofthe load are those due to compression at the reversals of direction ofthe load and to centrifugal force. There is a permitted internaldisplacement going on all the time. because the constituents of the loadare never at rest, but the cross-sectional area of the load as a wholeapproximates uniformity, and in the structures illustrated for use inthe practice oi the invention there may be, unless and until wearail'ects the situation, a maintenance of the cross-section substantiallyconstant along the path of the load.

The reducing action continues throughout the cycle-The reducing actionis a compound one. It is not limited to the impact or pressure caused bythe reversal of direction of the load at each reciprocation. Itcontinues throughout the stroke in the form of radial or tangentialpressure primarily against the bottom 2| of the chamber 20. In thparticular structure shown in the present specification, this continuingreducing pressure or thrust results, for example, from the centrifugalaction caused by the rotary oscillation of the chamber 20 about itsaxis. The time represented by the reversals of direction is only afraction of a cycle, and to continue the reducing action throughout thestroke, something must be provided for the charge to work against. Byemploying an arcuate bottom 2i, and by oscillating the chamber 20 as awhole about the center X, I compel the load to move as it were uphillwhenever it moves in relation to the chamber. This causes a tangentialthrust or pressure and thus we can say that the load is subjected tothree diflerent reducing actions. There is in the first place the radialcentrifugal pressure of the load against the lower portion of thechamber 20. There is the tangential pressure caused by movement of theload in relation to the chamber 20, which causes the load to climb upthe ends of the chamber. Finally, there is the impact or compression ofthe load against the chamber end. At all times, during the cycle ofreduction, the load is being pressed against a reacting member whichcauses pressures to be set up within and on the load. It is probablethat some '75 per cent of the capacity, in my mill, is produced bypressures operating between the actual reversals or terminal impacts. Ifind the employment of an arcuate bottom or chamber a convenient meansfor obtaining my result. The are of the chamber need not coincid withthe arc of travel or the chamber, as is indicated by the chamber 20' ofFig. 10 whose pivot, indicated by the small unnumbered circle, is belowthe center from which the arc of the chamber is swept and there is roomfor much variation in contour. While I prefer a chamber havingcurvilinear bottom and top walls, it is within the spirit of myinvention to employ walls having parts at slight angles to each other,as indicated in the construction of chamber 2B" in Fig. 11; or to employa chamber having upturned ends which need not be curvilinear, asillustrated by the construction of the chamber 20" of Fig. 12.

Stage reducti0n.-A further advantage and effect of my mill, and onewhich contributes to the ready escape of the reduced particles from thechamber 20 through the apertures 22, is the inherent classifying actiondue to centrifugal force. All particles are thrust centrifugally towardthe wall 2| during the intermediate portion of each stroke. The reversalof movement at the end of the stroke, with its interruption of thecentrifugal and the tangential thrust above discussed, allows theparticles to rearrange themselves. As the smaller particles are denserfor a given volume than the larger, they tend to displace the largerparticles toward the center, and to monopolize the periphery or exterioror bottom of the crushing zone, because their size permits readieroutward penetration in a radial direction. This centrifugal force tendsto drive and to hold every particle out as far from the center ofrotation or oscillation as it can go. As will appear, for example inFigures 5 and 7, the fine particles G2 of the media and H2 of the work,crowd out against the wall 2 I. The intermediate sized particles 6-4 ofthe media and H-l of the work, occupy an intermediate zone or stratum.The largest particles G of the media and H of the work, are stratifledat the top of the crushing zone. As reduction takes place, the

finer particles sift or escape downwardly through the load and pass outthrough the apertures 22. The tendency of centrifugal force to move thesmaller and denser particles to the periphery is made relatively easy bythe continuous reversals of direction of the load as a whole, whichfavor the progressive reorganization of the particle structure of theload.

Force feed, passage, and discharge.The inter- I mittent centrifugalthrust upon the material undergoing crushing supplements the gravitalmovement of particles to the reduction zone, through the reduction zone,and out of the reduction zone, all in connection with the abovedescribed classification reduction. The centrifugal force acts on thematerial D between the passage walls 26 of the feed passage. This massof material, which is under constant grav tal thrust downwardly againstthe load, has its gravital thrust intermittently strengthened by acentrifugal thrust. It takes considerable force to drive the feedagainst the tightly packed mass of balls and particles of the load. Whensufficient of the finer particles have escaped to shorten the load andto permit a slight unmasking of the feed aperture bounded by the walls26, it takes force to drive the feed through this opening in the shorttime that it is uncovered at the ends of the stroke. This centrifugalaction not merely contributes to the feeding thrust and to the carryingof the reduced particles through the load as a whole, but contributes tothe tendency of the reduced particles at the bottom of the load toescape through the passages 22. As above pointed out, this centrifugalthrust would not be so eflective if it were not discontinuous. Everyreversal of direction of the load E, and of the feed mass D, permitsrearrangement of particles and contributes radically to the efflciencyof the centrifugal or tangential thrust. Their conjoint and successiveaction is an important feature of my invention, and contributes greatlyto the eiiiciency of my mill.

Self regulation of feed and volume-In my mill I provide a constant andself regulated feed. This is of vital importance, because, by using it,I avoid loss of emciency by underfeeding, with no possible risk ofoverfeeding. The entire line of feed, including the bodies of materialindicated at A, B, C and D in Figure 5, exerts a cumulative pressureupon, and body D actually rests in part upon, the top of the charge E.The material in the hopper I can be piled as high as the operatorwishes. The passage 2 may be constantly choked and the entire mechanismrun at so-called choke feed. No matter how high the material may bepiled in the hopper I, there is no possibility of choking or overfeedingthe reduction chamber 20. The load or chamber contents regulates theentrance rate at every instant. I obtain this result in part byemploying a form of chamber such that the load fills the chambercross-sectionally throughout the length of the load. My preferred way ofobtaining this result is to emplo a reduction chamber 20, the

. cross-sectional area of which approximates uniformity and whichdesirably is substantially constant throughout its length. The load Emoves bodily back and forth along the chamber 20 without deformation ofits bounding surface. The intake passage bounded by the walls 2G is ofsuch length, and is so located that the load itself blocks the inletwhen the load volume is at a predetermined maximum. This prevents thepenetration of additional particles until sumcient reduced particleshave been discharged to make room for such additional particles. Theinstant that enough particles have been discharged to permit theaddition of new particles, such new particles are delivered into thecharge from the waiting mass D, by gravital thrust or by the reinforcingcentrifugal thrust.

Avoidance of short circuit-Another advantage of my mill, effective inconnection with the automatic feed control and the classified reductionabove discussed is that it renders practically impossible the passage ofunreduced particles through the reduction zone. Virtually all thematerial, admitted from the mass D must pass through the load andthrough the crushing media from top to bottom, before escaping from theapertures 22. The small part of the material that enters at either endof the load is caught by the oncoming edge of the load E and is pushedagainst the chamber wall or the chamber end or both. I maintain the rateof reciprocation or oscillation of the chamber so high that this endmaterial cannot drop through the chamber 23 before the load as a whole,or the crushing medium, overtakes it, This is particularly the case,since the load as a whole is maintained relatively compact and solid,filling up the entire cross-sectional area of the chamber 20 throughoutthe length of the load. As a result of this prevention of shortcircuiting the size or quality of the product is independent of thefrequency of oscillation. This is of importance, as freeing me of thenecessity of closely adherirg to an optimum speed, a matter of necessityin conventional ball and impact mills.

Product size control.-In my employment of a relatively confined orcompact load, not only do the constituent particles have a generallyfixed relation to each other, as they classify by size, but the same istrue of their interstices. I provide sumcient movement within the chargeitself to prevent stagnation and to make possible the passage of theparticles through the charge. I obtain this result by my alternation oflongitudinal and transverse reduction pressure. When the particlesclassify or stratify by size, as they do, as shown for example in Figure5, the lower stratum composed of the small media particles G2 the smallwork particles H2, serves as a sizing bed because of the small size ofthe interstices between particles. Only particles small enough to passthrough the interstices of this layer can escape through the apertures22. Similarly, the higher strata of media and particles size or controlthe particles passing through to the lower part of the reduction zone.The product ultimately passing through the media issubstantially uniformin size. And this size is controlled by the size of the media particles.The work particles of each stratum escape to a lower stratum as soon asthey are reduced to a size substantially below the size of the mediaparticles of that stratum. Therefore, by altering the size of the media,I can alter the size of the interstices, and control the size of theparticles passing through and discharging from the load. All that isnecessary in order to effect such a change, is to change the size of themedia in the chamber III.

Pumping action.The form of my chamber 20 being such that the load flilsit in cross-section, a pumping action is developed at each end of thechamber at each reciprocation of the load. The load acts like a pistonwithin the cylinderlike chamber. This pumping action serves a two-foldpurpose; iirst, iniorcing out material which has been reduced to propersize, thus promoting discharge; and second, compressing air or other gasremaining in that portion oi the chamber, which compression serves totake up some of the shock of contact.

Power saving at no load.Inasmuch as the charge is of small volume inrelation to the cubic content of the reduction chamber 20, as shown inFigure 6, and since, owing to the curvilinear shape of the chamberbottom 2 I, the charge tends to stay in the bottom of the chamber 2|,out of contact with the ends II, I am able to avoid any working contactbetween the media and the ends 24 of the chamber 20 when the chamber isrunning empty, or if the load falls below a predetermined minimum. Inother words, with insuflicient material present, the bottom of thechamber 20 will travel beneath the medium, but, the oscillation of thechamber will be insuflicient to cause the reduced load to engage thechamber ends N. The load is held by gravity in an intermediate or idleposition. No reduction takes place, and no wear, other than the slightwear against the bottom 2|. And, what is exceedingly important, no poweris consumed except the frictional power of the mechanical system. Butthis "no load" operation involves no delay in the resumption of normaloperation. When suiflclent material enters to build up the load volumeto a size where the ends of the chamber engage the load, action startsagain, and reduction takes place and continues as long as enoughmaterial passes down between the inlet walls 28 to maintain a sumcientload in the chamber 20. This actionis so sensitive, and so certain, thatin practice I have been able to cause a mill to operate for a second ortwo on full load, followed by a second or two of no load. A change oi afew cubic inches in chamber contents volume, at the critical point, isenough to throw the machine from full load to no load or from no load tofull load. the period of building up or dropping amounting only to asecond or two. In the use of my invention the power consumption is morenearly proportioned to the work done than in any other mill or machineknown to me. In practice the no load power consumption need not be overten per cent of the full load power consumption.

While the feature Just described has the distinct advantages pointedout, it will of course be understood that the volume of media may bevaried at the will oi the operator by adding or subtracting balls; and,in any event, the employment of my invention, in its broader aspects, isnot dependent upon the employment oi any particular or predeterminedvolume of media.

The feeding arrangement-I flhd it desirable to feed my oscillating millnear the center of oscillation. The feed opening defined by the walls 28has the same angular amplitude oi movement as the chamber 20. Butwhereas the charge is reciprocated through a very substantial arc in thechamber 20, the material in the feed passage is constrained tma muchsmaller are by the confining walls I6. ,The feed mass D, thereincontained, is not permitted to agitate, and by plug ing up the wholeteed passage, prevents any unintended retrograde escape 01 particlesfrom the charge E. It serves as a seal for the top oi the chamber 20,and assists in maintaining the charge in its desired compact condition.

The shield 3| and the sleeve I! are advantageous in maintaining aconstant feeding connection. The opening is never closed or obstructed,even at the extreme ends of the stroke.

In causing the mass D to serve as a plug or seal for the inlet openingto the chamber 20 I find that employing tapered walls 26 isadvantageous. There is no chance for material from the chamber 20 toescape when the mass of material D is present. In the event that thismaterial is used up by underi'eedlng, the tapered sleeve ll still servesas a baflie. The escape oi balls or material is eflfectively prevented.

The mechanics of my apparatus and method. In my opinion the majorreduction I obtain results from the lateral thrust against the walls,and especially the bottom wall 2 I. of the chamber 20. Pressure onmaterial being reduced is necessary for reduction, but pressureaccompanied by movement is vastly more effective than pressure alone. Iprovide both to a high degree. The centrifugal or radial pressure is dueto the partial rotative motion of the load about the axis of osciliatlonoi the chamber 2|). It results in a radial compression of the load. dueto its mass, radius and velocity, which is greatest at each stroke whenthe other pressures below described are at a minimum. My second sourceof reduction is the inertial or longitudinal pressure developed by thereversal oi the load due to the reversal in direction of movement of thechamber 20. It is not a mere impact, but is smoothed out and extended.Instead 01' moving my load, without choke or drag,

between changes of direction, I subject it to a constant pressureintermediate its reversal of direction, as above described. I employ notmerely the direct radial thrust or pressure above discussed, but thetangential thrust of the load when it moves in relation to the chamber.It tends to move rectilinearly or tangentially, but is constrained tofollow the arc and not the tangent. This tangential thrust, whichprecedes the terminal impact. robs the terminal impact of some of itssharpness, and also returns to the power source some of the energy putinto the mass during the acceleration. The changes in thrust resultingfrom the alternation between longitudinal or inertial pressure andtransverse (radial or tangential) pressure, promote settling and limitedmovement in the mass without allowing the mass as a whole, or itsconstituent parts, to move freely about. Another contribution tolongitudinal pressure results from my employment of a relatively longload, analogous to the eiiect of a long string of freight cars. The verylength or the load increases the time during which the impact resultingfrom the reversal of direction is felt through the load as a whole.

By the employment of these various features I am able vastly to reducepower use and power costs, while increasing reduction efliciency. I amable to obtain very accurate sizing, and to vary my sizing at will. Inmy sizing and in my reduction results I am not closely limited to anoptimum rate of oscillation.

It will be understood that whereas I have illustrated a mechanism inwhich the reduced particles pass down a hopper 35 to an outlet ll, anysuitable means may be employed to return oversize particles, if any, forrecrushing. It is thought to be unnecessary to illustrate a mechanismfor this purpose, since elevators, conveyors and recirculating devlcesare well known in the art. I wish to make it clear, however, that myinvention is not limited to single pass reduction, but

is equally applicable to closed circuit reduction in which part or allof the discharged material is returned to the reduction chamber forfurther reduction.

It will be understood that when, in the claims, 1 specify that thereducing chamber is of uniform cross-sectional area from end to end, Iam alluding to the ends 24 against which the load abuts and to thesubstantially constant distance separating the walls 2| and 23, and notto the side walls 20.

And it will further be understood that whereas in the specification orclaims I describe the reduction chamber as being substantially uniformor constant, or generally or approximately uniform in cross-section orin cross-sectional area, from end to end thereof, I wish such terms tobe used with suilicient flexibility to include not only slightvariations in cross-sectional area from point to point along thechamber, such as are inevitable under ordinary manufacturing conditions.but also variations in cross-sectional area resulting from inequality ofwear, it any.

And whereas it is desirable that said chamber 20 be of generallyconstant cross-sectional area from end to end thereof, it will beunderstood that I consider it within the scope of my invention to permitslight variations in cross-sectional area to a degree insufficient toimpede or change the character of the reduction which takes place insuch chamber or to preclude the described operation of the chambercontents in regulating feed.

While I have in this application specifically described one form andthree modifications which my invention may assume in practice, it willbe understood that this form and these modifications have been shown forpurposes of illustration and that the invention may be further modifledand embodied in various other forms without departing from its spirit orthe scope of the appended claims.

I claim:

1. In a mill, means providing a size-reducing chamber supported formovement back and forth, said size-reducing chamber elongated in itsdirection of back-and-forth movement, at least approximating uniformityin cross sectional area throughout the major portion of its length,provided with discharge means through which material of small enoughsize to go through the same may pass while the chamber is in motion, andhaving means for the introduction into said chamber during the operationof the mill of material to be processed, including a feed passagecommunicating with said chamber through an aperture intermediate theends of the chamber in a wall which extends longitudinally of thelatter, and means for moving said chamber back and forth. said chamberof such dimension between said aperture and the opposite surface of saidchamber, said chamber and said aperture of such relative lengths anddisposition and said chamber-moving means imparting to said chambermovement at such rate and of such amplitude, that during normalcontinuous size-reducing operation the chamber load will be reciprocatedbetween the ends of the chamber as a substantially compact masssubstantially filling the entire cross-section of the chamber throughoutthe major portion of its own length and sweeping across the feedaperture and controlling the ingress of material awaiting entrance tothe chamber at said feed aperture, and coacting with said feed apertureto preclude the building up of the volume of the mass sufficiently toiill the chamber completely.

2. A mill as defined in claim 1, in which the feed aperture opensthrough the top wall of the chamber and in which the chamber, at leastthroughout the major portion of its length, at least approximatesuniformity in cross section.

3. A mill as defined in claim 1, in which the size-reducing chamber issupported for arcuate movement and has its walls respectively nearest toand farthest from the axis of its arcuate movement arcuate, in whichsaid chamber at least approximates uniformity in cross sectionthroughout the major portion of its length on planes including its axisof arcuate movement, and in which the feed aperture lies in the wallnearest the axis of chamber movement.

4. A mill as defined in claim 1, in which the chamber is of a dimensionlongitudinally at least three times its dimension between the feedaperture and the opposite surfac of the chamber, and in which saidchamber is also of a dimension longitudinally at least three times thedimension of the feed aperture longitudinally of the chamber.

5. In a mill, means providing a size-reducing chamber supported forback-and-forth movement, said size-reducing chamber elongated in itsdirection of back-and-forth movement, approximating uniformity in crosssectional area throughout the major portion of its length, provided withdischarge means for the elimination from the chamber contents duringoperation, of material below a predetermined size, and having feedingress means between its ends having associated therewith supply meansadapted to deliver materlal to said feed ingress means at a rateinexcess of the size-reducing capacity of the mill, and means for movingsaid chamber back and forth, said chamber of such dimension normal toits path of movement, and said chamber-moving means imparting to saidchamber movement at such rate, that the contents of said chamber aremaintained substantially compact in a mass conforming to the crosssection of said chamber, and said chamber and said feed ingress means ofsuch lengths and relative disposition and said chamber-moving meansimparting to said chamber such movement both as to velocity andamplitude that with material constantly maintained at said feed ingressmeans and awaiting entrance to said chamber the chamber contents arereciprocated between the ends of said chamber and maintainedinsufficient completely to fill the chamber but sufllcient to maintainsaid chamber substantialLy filled in cross section at its centralportion at all times.

6. In a reduction mill, a reduction chamber arcuate in verticallongitudinal section and at least approximating uniformity in transversecross sectional area throughout substantially its full length from endto end, means for delivering to said chamber the material to be reduced,means for withdrawing from said chamber the reduced particles, and meansfor swinging said chamber about a transverse axis, the length and radialdimension of said chamber, its path of swing, and its speed of movementpredetermined to maintain the chamber contents in a relatively compactmass, filling substantially the full cross sectional area of saidchamber for more than half but less than the entire chamber length, inall of its various positions in said chamber, and to subject saidchamber contents through movement by and relative to said chambersuccessively to radial, tangential and longitudinal pressure.

'7. In an apparatus of the character described, an oscillating chamberhaving a curved internal bottom surface at least approximating incurvature an arc whose center coincides with the axis of oscillation ofsaid chamber and having an upper bounding surface of at leastapproximately concentric curvature provided with a feed intake openingand having further abutment-providing ends, said chamber at all pointsbetween its ends at least approximating uniformity in dimensionradially, said dimension materially less than the distance between theaxis of chamber oscillation and the point most adjacent thereto in saidcurved internal bottom surface.

8. In a mill, a movably mounted size-reducing chamber supported formovement in opposite directions along a predetermined path, said chamberelongated and substantially arcuate in its planes of movement and of auniform width internally throughout its length and of comparativelysmall but uniform dimension normal to its path of travel, means forintroducing material into said chamber including a feed openingsubstantially midway between its ends, means for discharging processedmaterial while said chamber is in motion, and means for moving saidchamber oppositely along said path, the length of said chamber, itsdimension normal to its path, the dimension of said feed openinglongitudinally of said chamber and the rate and amplitude of movement ofsaid chamber such that when said mill is operating at capacity duringeach movement of said chamber in one direction along its path the sameis filled completely full throughout the central zone of its lengthwhile both ends thereof are empty, whereby the chamber contents controlthe feed.

9. In a reduction mill, a reducing chamber the cross sectional area ofwhich at least approximates uniformity from end to end of the chamber,means for imparting rotary oscillation to said reducing chamber about agenerally horizontal axis positioned above the reducing chamber, theupper and lower walls of the reducing chamber being at leastapproximately concentric and struck from said axis and further being ofsubstantially equi-angular arcuate extent, a feed passage openingthrough the upper wall of said reducing chamber, and means formaintaining feed therethrough during the oscillation of the reducingchamber, the lower wall of the reducing chamber being apertured topermit the escape of the reduced particles.

10. In a mill, a size-reducing-chamber-providing member mounted forpivotal movement about a horizontal axis, means for imparting theretorapidly alternated arcuate movements in opposite directions, saidchamber-providing member having an arcuate chamber formed therein of anangle of arc materially greater than the angle of such arcuatemovements, said chamber having end walls and longitudinally extendingwalls and of substantially uniform cross section, betweensaid end walls,on radial planes, and said longitudinally extending walls includingnopatively closely spaced concentric inner and outer walls, the rate ofchamber movement and the spacing of said concentric walls so predetethat the chamber movements cause the chamber contents to contact theopposite ends of said chamber in alternation and concurrently tocontact, with substantially equiangular extent, said inner and outerwalls, during size-reduction.

11. In a mill, 8. slze-reducing-chamber-providing member supported forarcuate movement about a substantially horizontal axis, and means forimparting thereto a rapid oscillation upon such axis, said memberproviding end walls and between the latter a size-reducing chamber ofgenerally uniform cross sectional area at substantially all pointsbetween said end walls on planes including said horizontal axis, andhaving upwardly concave generally concentric upper and lower walls witha feed opening through the said upper wall adjacent the center thereofand with said walls so spaced radially that with said feed openingentirely closed by a level surface of chamber contents resting on theouter wall of said chamber said chamber still provides material room forthe reciprocation therein of such contents.

12. In a mill, a size-reducing-chamber-providing member mounted forswinging movement upon a substantially horizontal axis and providing anarcuate chamber having end walls and at least approximately concentricinner and outer walls and at least approximating uniformity in crosssectional area on transverse planes normal to said concentric walls atsubstantially all points between said end walls and of such extent andcurvature that a straight line connecting the central points in the endsof said chamber falls at its middle point above the central point in thecurve of the inner wall of said chamber, means for supplying material tosaid chamber during oscillation thereof and for discharging processedmaterlal therefrom also during operation, and means for oscillating saidmember rapidly about its pivot through a path such that the centralpoint in the curve of the inner wall of said chamber always lies below ahorizontal plane including said horizontal axis, said chamber having theinterior thereof clear from end to end thereof for the free movementalong said outer wall, under movements imparted thereto by said endwalls, of the chamber contents.

13. In a mill, means providing a size-reducing chamber supported forswinging movement, said size-reducing chamber elongated in its directionof swinging movement and having upturned portions at opposite sides ofits center as viewed from the side. of at least approximately uniformcross sectional area throughout at least the major portion of itslength; provided with discharge means for size-reduced material throughwhich adequately small material may freely pass while said chamber is inmotion, and having feed ingross means between its ends having associatedtherewith supply means adapted, while said chamber is in motion, todeliver material to said feed ingress means at a rate at least equal tothe sine-reducing capacity of the mill, said chamber having wallsenclosing the same imperforate save for said discharge and feed ingressmeans. and means for oscillating said chamber through such an are thatits ends are both always higher than an intermediate portion, saidchamber of approximately uniform dimension from end to end normal to itspath of movement and of a length at least twice its dimension normal toits path of movement, and the ratio of chamber length to the length,longitudinally of said chamber, of said feed ingress means and the rateof chamber oscillation such that the chamber contents are reciprocatedin a substantially compact mass within said chamber in contact with andsustaining the head of material in said supply means awaiting ingress tosaid chamber.

14. In combination, a support, a power-oscillated supporting elementswingably mounted in depending relation on said support, and a millingchamber fixed to said supporting element ior arcuate movement thereby,said milling chamber having concentric upper and lower walls with a feedopening in its up r wall in the longitudinal central portion thereof andwith the end portions of said upper wall closed and with its lower walltraversed largely throughout its length with discharge openings, theends of said chamber substantially diametrically opposite each otherwith reference to the arc of swing of said chamber and said chamber ofgenerally uniform cross sectional area substantially throughout itslength on planes including its center of curvature and of a radialdimension materially less than half the radius with which its bottom isformed.

15. In a mill, means providing a size-reducing chamber supported foroscillatory movement about a pivot, said size-reducing chamber elongatedin its direction of oscillatory movement and having relatively high endsand a low median portion, approximating uniformity in cross sectionalarea throughout the major portion of its length, provided with dischargemeans for size-reduced material through which material of small enoughsize may pass while said chamber is in motion, and having feed ingressmeans be-. tween its ends having associated therewith supply means of aconstruction to deliver material to said feed ingress means at a rate inexcess of the size-reducing capacity of the mill and under a centrifugalforce as a result of the movement of said chamber, said chamber havingwalls enclosing the same imperforate save for said discharge and saidfeed ingress means, and means imparting such an oscillation to saidchamber as to compact the chamber contents alternately against thechamber ends, leaving the other ends empty, and cause the same to exerta substantial centrifugal force against the outer wall of said chamberduring transit from end to end thereof, said chamber of approximatelyuniform dimension from end to end normal to its path of movement and ofa length beyond either end of said feed ingress means greater than saiddimension normal to its path of movement.

16. In a mill, a chamber-forming member supported for oscillatorymovement and providing an elongated, relatively shallow chamber havingends materially higher than its median portion when said chamber is inits mid position and adapted to contain during operation a loadcomprising mingled size-reducing media and material to be reduced insize and having its interior free from obstructions to the free movementof such load longitudinally within said chamber under forces impartedthereto by the chamber ends, means for imparting to said chamber-formingmember rapidly-alternated opposite movements of a speed and amplitude tocause bodily movement of the chamber contents as a mass relative to thechamber, in frictional contact, under centrifugal force, with th lowerwall of said chamber, and compacting of the chamber contents alternatelyat the opposite ends of the chamber and the occupancy of the spacetherein from top to bottom of said chamber throughout more than half butless than the entire length thereof, and a feed opening into saidchamber across which the chamber contents sweep during movement relativeto the chamber.

1'7. In a mill, means providing a size-reducing chamber supported forreciprocatory movement, said size-reducing chamber elongated in itsdirection of reciprocatory movement, of substantially uniform crosssectional area throughout its central and at least the major remainingportions of its length, provided with discharge means effective todischarge material small enoughto pass therethrough, upon the attainmentof such material thereto, while the chamber is in motion, havingassociated therewith supply means for material to be reduced, and havinga feed opening between its ends with which said supply meanscommunicates, and means for imparting to such chamber reciprocatorymotion, said feed opening of such dimension longitudinally of saidchamber relative to the overall chamber length, and said chamberreciprocating means imparting to said chamber motion of such amplitudeand at such speed that the chamber contents are caused to move as arelatively compact mass alternately with, and between the ends of. saidchamber and to assume and maintain a volume adequate at least to fillthe space within said chamber at one end of said feed opening and alsosubstantially the entire space opposite said feed opening while leavinga substantial unfilled space within said chamber,

whereby with material constantly maintained at and awaiting admissionthrough said feed opening, relative reciprocation between the chambercontents and said chamber takes place and the chamber contents regulatethe introduction of new material.

18. In a mill, means providing a size-reducing chamber supported forreciprocatory movement, said size-reducing chamber elongated in itsdirection of reciprocatory movement, approximating uniformity in crosssectional area throughout the major portion of its length, provided withdischarge means through which material of small enough size may passwhile said chamber is in motion, and having feed ingress means betweenits ends having associated therewith supply means adapted to deliver,while said chamber is in motion, material to said feed ingress means ata rate in excess of the size-reducing capacity of the mill, and meansfor reciprocating said chamber, said chamber of such dimension betweensaid feed ingress means and the opposite side of said chamber, saidchamber and said feed ingress means of such relative lengths anddisposition, and said chamber reciprocating means imparting to saidchamber movement of such rate and amplitude that with materialconstantly maintained at said ingress means and awaiting ingress to saidchamber the chamber contents are maintained automatically, while saidmill is in operation, sufficiently less in volume than the volume ofsaid chamber so that relative reciprocation between said contents andsaid chamber may take place, but yet adequate in volume to occupy atleast one-half the overall length of said chamber throughout its entirecross section, during normal mill operation.

19. In a mill, a frame, a pendulum pivotally supported on said frame foroscillatory movement about a pivot and having an elongated sizereducingchamber therein of approximately semi-annular form disposed with itsconcave side towards said pivot, said pendulum further providing a feedpassage opening into said chamber at a locus which is substantiallyequally spaced from the ends of said chamber and at the same distance assaid chamber ends from said pivot, discharge means for size-reducedmaterial along the wall of said chamber more remote from said pivot, aquantity of free size-reducing media in said chamber, and means forimparting to said chamber alternate opposite movements of an amplitudeand at a velocity to throw the chamber contents back and forth betweenthe chamber ends during normal size-reducing operation.

20. In a mill, means providing a size-reducing chamber supported forswinging movement, said size-reducing chamber elongated in its directionof swinging movement and having upturned portions at opposite sides ofits center as viewed from the side whereby the ends of the chamber arematerially higher than the highest part of the center thereof when saidchamber is in mid position, said chamber further approximatinguniformity in cross sectional area throughout the major portion of itslength, provided with discharge means for size-reduced material throughwhich adequately reduced material may freely pass while said chamber isin motion, and having feed ingress means between its ends havingassociated therewith supply means adapted to deliver material to saidfeed ingress means at a rate at least equal to the size-reducingcapacity of the mill, said chamber having walls enclosing the sameimperforate save for said discharge means and feed ingress means andbeing clear from end to end thereof for the free movement of itscontents between its ends, and means for oscillating said chamberthrough such an are that its ends are both always higher than anintermediate portion, said chamber of substantially uniform dimensionfrom end to end normal to its path of movement and of a length aplurality of times its dimension normal to its path of movement.

21. In a mill, a chamber-forming member providing an elongatedrelatively shallow chamber having end walls and of like cross sectionsubstantially throughout its length between said end walls and adaptedto contain during operation a load comprising mingled size-reducingmedia and material in process, means for imparting to saidchamber-forming member rapidlyalternated opposite movements along apredetermined arc to which the chamber in said member generally conformsin curvature and of a speed and amplitude to cause bodily movement ofthe chamber contents as a mass relative to the chamber and packing ofthe chamber contents alternately against the opposite ends of thechamber while the opposite chamber ends are respectively empty, andmaintenance of said chamber contents in a substantially compact mass atall times filling throughout its own length substantially the fullchamber cross section, and means providing a feed supply connectionhaving a feedopening into said chamber in a position spaced from theends of said chamber and covered by the chamber contents as the lattermove between the chamber ends.

22. In a mill, means providing a reverseiy arcuately moved chambergenerally arcuate in its planes of movement and approximating uniformityin cross section on planes including the axis of movement of suchchamber at substantially all points between its end portions. having afeed connection terminating in an intake opening free size-reducingmedia in said chamber, said size-reducing media and material admittedthrough said feed opening forming a mass moving as a whole from end toend of said chamber through a wall of said chamber, and a charge of andtraveling alternately back and forth across said opening while said millis in operation and acting as a gate therefor.

23. In a reduction mill, a reducing chamber having concentric upper andlower arcuate walls and a cross sectional area which is substantiallyuniform from end to end, the ends of said reducing chamber beingupwardly turned, a feed passage having communication with said reducingchamber through the upper wall of the latter at a point lower than theopposite extremities of said upper wall, the longitudinally oppositewalls of said passage tapering upwardly and inwardly toward each other,said chamber having the upper walls of its upwardly turned ends each ofat least as great extent as the length of the communication with saidchamber of said feed passage, and means for unitarily swinging thereducing chamber and feed passage about a center adjacent the upper endof said feed passage and from which said chamber is materially spaced atall points.

24. In a reduction mill, a generally curvilinear reducing chambermounted for oscillatory movement about a generally horizontal axis, thecross section of said chamber being substantially constant from end toend, the ends of said reducing chamber having a substantial upwardextension, means for imparting rotary oscillation to said chamber aboutsaid axis, th bottom wall of said chamber being provided with aperturesto permit the escape of reduced particles, a feed passage memberextending upwardly from the upper wall of said chamber to a pointadjacent the axis of rotation of the chamber, said reducing chamberclosed at its top except for communication through said feed passagemember, a fixed feed spout, and means including relatively oscillatableparts fixed respectively relative to said feed spout and to said feedpassage member for maintaining a constant feed connection between saidfixed feed spout and said feed passage during the rotary oscillation ofsaid chamber.

25. A rocker including a barrel, a feed neck fixed to said barrel and incommunication with the interior thereof, and an oscillating millingchamber fixed relative to and in communication with the interior of saidfeed neck, said barrel cut away at the upper portion thereof, astationary saddle covering said barrel and in close adjacency theretoand having a feed opening therethrough registering with the cut-awayportion of said barrel, and means for supplying material to said saddlefor delivery through the feed opening thereof into said barrel andthrough said feed neck into said milling chamber.

26. In a mill, a saddle having a feed opening therethrough and means forsupplying material to said opening, a barrel flttingsaid saddle andhaving material -conducting passage means therein communicating withsaid opening, a support member in rigid relation to said barrel andosciliatable therewith about the axis of said barrel and providing anelongated arcuate size-reducing chamber and a radial feed passageconnecting said material-conducting passage means and the interior ofsaid chamber, a charge of size-reducing media in said chamber, and meansfor imparting rapidly reversed, pivotal movement to said barrel andsupport member to effeet a size-reducing process throughout saidchamber, at the zone of communication of said feed passage with saidchamber, and also adjacent the communication between said saddle andsaid barrel.

27. In a reduction mill, a reducing chamber mounted for oscillationabout a generally horizontal axis, said reducing chamber conforminggenerally in curvature to an arc struck from a point in said axis, thecross section of said chamber being approximately constant from end toend, means for imparting to said chamber rotary oscillation about saidaxis, the outer wall of said chamber being provided with apertures topermit the escape of reduced particles, a feed passage member extendingupwardly from the upper wall of said chamber, a sleeve associated withthe upper end of said feed passage member, surrounding the axis ofoscillation of the chamber, a fixed feed spout, a guard memberassociated therewith, in relatively rotary shielding relation with saidsleeve, said guard member and sleeve being apertured in line with eachother, the apertures of the sleeve and guard being of sufficient sizeand their relative movement such as to maintain a feed connectionbetween said feed spout and said sleeve of constant cross sectionalarea.

28. In a reduction mill, an elongated reducing chamber having end wallsand longitudinally extending top, bottom and side walls and ofapproximately uniform cross sectional area between the end portionsthereof, means for feeding material thereto including a feed aperturein, and adjacent the central portion of, one of said longitudinallyextending walls of said chamber, discharge apertures in anotherlongitudinally extending wall of said chamber, the walls of said chamberimperforate save for said feed and discharge apertures, means forsupporting said chamber for oscillation about an axis from which itdepends, means for imparting a predetermined longitudinal bodilyoscillation to said chamber about said axis, said chamber so formed thatthe end portions thereof are spaced from each other by less than thelength of said chamber along its center line and the end portions ofsaid chamber being upwardly extended relative to the central portionthereof to such a degree that during chamber oscillation the extremitiesof said chamber are both at all times higher than the lowestintermediate portion thereof, and a charge of free reducing mediaconfined in said chamber by the walls thereof and movable bodily withand also relative to said chamber and insuilicient in volume, inrelation to the length of excursion of said chamber, to engage either ofthe chamber ends when the mill is running below a predetermined minimumload.

29. An oscillating size-reducing chamber having upwardly concave arcuatetop and bottom walls and further having end walls which alternatelyengage the chamber contents once in each cycle during milling, saidchamber containing a charge of freely movable sizereducing media all ofwhich are free to move relative to each other in any direction except asrestricted by the chamber walls and each other and whose most remoteelements are spaced from each end of the chamber when the latter isstationary and in mid position, and means for moving said chamber in apath conforming in curvature to said bottom wall, the length arcuatelyof said bottom wall so exceeding the chamber movement that said media donot ensue the end wal s o said chamber when unaccompanied by material insaid chamber, and means for introducing material into said chamber whilethe latter is in motion.

30. In a mill, a support, an element pivotally mounted on said supportand oscillating like a pendulum rapidly during milling and having anarcuatechamber formed therein having inner and outer, at leastapproximately concentric walls whose curvature conforms approximately toarcs of circles struck from its axis of oscillatory movement and endwalls alternately engaging the chamber contents, and a free charge ofsize-reducing media within said chamber comprising elements of widelyvarying size classified in strata during the oscillation of said chamberwith the larger elements traveling on the shorter radii, and means foradmitting and discharging material relative to said chamber duringchamber oscillation arranged to provide for passage of material as itssize is reduced through said strata.

31. In a reduction mill, an arcuate reducing chamber the cross sectionalarea of which at least approximates uniformity throughout the arcuateextent of the chamber, means for imparting rotary oscillation to saidreducing chamber about a generally horizontal axis positioned above thelower portions of the reducing chamber, the upper and lower walls of thereducing chamber being at least approximately concentrio and struck fromsaid axis and further being of substantially equiangular arcuate extent,a feed passage opening through the upper wall of the central portion ofsaid reducing chamber, and means for maintaining feed therethroughduring oscillation of the reducing chamber, the reducing chamber beingapertured in the lower wall thereof to permit the escape of the reducedparticles, the ratio of the arcuate extent of said chamber to that ofsaid feed passage and the rate and amplitude of chamber oscillationbeing such that the chamber contents are reciprocated in said chamberand during normal size-reducing motion are continuously maintained, atleast adjacent the central portion of the opening of the feed passageinto the chamber, in a compact mass occupying the full cross section ofsaid chamber.

32. In a reduction mill, an arcuate reducing chamber the cross sectionalarea of which at least approximates uniformity throughout the arcuateextent thereof, means for imparting rotary oscillation to said reducingchamber about a. generally horizontal axis positioned substantially atthe center of curvature of the reducing chamber, the radially inner andouter walls of the reducing chamber being at least approximatelyconcentric and struck from said axis and further being of substantiallyequal arcuate extent, a feed passage opening through the radially innerwall of said reducing chamber, and means for maintaining feedtherethrough during the oscillation of the reducing chamber, theradially outer wall of the reducing chamber being apertured to permitthe escape of the reduced particles.

33. In a reduction mill, an arcuate reducing chamber the cross sectionalarea of which at least approximates uniformity throughout the arcuateextent thereof, means for imparting rotary oscillation to said reducingchamber about a generally horizontal axis positioned substa tially atthe center of curvature. of the reducing chamber, the radially inner andouter walls of the reducing chamber being at least approximatelyconcentric and struck from said axis and iurther being of substantiallyequal arcuate extent whereby a load within said chamber is reciprocatedupon chamber oscillation in a zone of reduction corresponding to asubstantial portion of an annulus, a feed passage opening through theradially inner wall of said reducing chamber adjacent the portionthereof which is lowest when said chamber is in mid position withrespect to its oscillatory movement, and means for maintaining feedtherethrough during the oscillation of the reducing chamber, theradially outer wall of the reducing chamber being apertured to permitthe escape oi the reduced particles.

34. In a mill, means providing a size-reducing chamber supported ioroscillatory movement for reciprocating a load therein, saidsize-reducing chamberbeing elongated in its direction of oscillatorymovement and having upturned portions at opposite sides of its lowermostpoint as viewed from the side and in its oscillation providing anarcuate zone of reduction of greater arcuate extent than the loadreciprocated therein, being of at least approximately uniform crosssectional area throughout at least the major portion of its arcuateextent. being provided with discharge means for size-reduced materialthrough which adequately small material may freely pass while saidchamber is in motion, and having feed ingress means between the ends ofthe zone of re-- intermediate portion, said chamber being of ap-'proximately uniform dimension at substantially all points traversed bythe load therein normal to its path of movement and being of an extentlongitudinal of the zone of reduction at least twice its dimensionnormal to its path of movement, and the ratio of chamber length to thelength, longitudinally of said chamber, or said feed ingress means andthe rate of chamber oscillation being such that the chamber contents arereciprocated in a substantially compact mass within said chamber incontact with and underlying the head of material in said supply meansawaiting ingress to said chamber.

85. In a. mill, means providing a size-reducing chamber supported foroscillatory movement with respect to its axiasaid size-reducing chamberbeing elongated in its direction or oscillatory movement and havingupturned portions at opposite sides or its lowermost point as viewedfrom the side and in its oscillation providing a zone oi. reduction ofgreater lengthwise extent than the load reciprocated therein, being ofat least approximately uniform cross sectional area throughout at leastthe major portion of its sizereducing extent, being provided in its wallremote from said axis with discharge means for size-redueed materialthrough which adequately small material may freely pass while saidchamber is in motion, and having teed ingress means in its wall towardsaid axis having associated therewith supply means adapted, while saidchamber is in motion, to delivermaterial to said feed ingress means at arate at least equal to the size-reducing capacity of the mill, saidchamber having imperforate walls save for said discharge and feedingress means, and means for oscillating said chamber about said axisthrough such an are that the ends of said zone of reduction always'aresubstantially higher than an intermediate portion thereof, said chamberbeing of approximately uniform dimension normal to its path of movementthroughout the path of load movement therein and of an extentlongitudinal of the zone of reduction at least twice its dimensionnormal to its path of movement, and the ratio of chamber length to thelength, longitudinally of said chamber, of said feed ingress means andthe rate of chamber oscillation being such that the chamber contents arereciprocated in a substantially compact mass within said chamber incontact with and underlying the head of material in said supply meansawaiting ingress to said chamber.

36. In a mill, 9. movably mounted size-reducing chamber supported formovement in opposite directions in a predetermined arcuate path, saidchamber being substantially arcuate in its planes of movement and beingarcuately elongated and of a uniform width internally throughout itslength and of comparatively small but uniform dimension normal to itspath of travel, means for introducing material into said chamberincluding a feed opening substantially midway of the path of loadmovement therein, means for discharging processed material while saidchamber is in motion, and means for moving said chamber oppositely insaid path and about an axis located at the center of curvature of saidarcuate chamber, the arcuate extent or said movement, the dimension ofsaid chamber normal to its path of movement, the dimension of said teedopening along the are 01' said chamber and the rate of movement or saidchamber being such that when said mill is operating at capacity duringeach movement 0! said chamber in one direction along ROBERT s. BUTLER.

CERTIFICATE OF CORRECTION.

Reissue Io. 21,910. September 50, 1914;.

ROBERT S. BUTLER It is hereby certified that error appears in theprinted of the above mmbered patent requiring correction as follows:Page 5, first column, 1111019, for the word "from" reed --dom-; and thatthe said Lettore Potent ehouldhe read with this correction therein thatthe name may confonn to the record of the case in the Patent Office.

Signed end see led this 18th day of November, A. D. 1914.1.

Henry Van Aredale,

(Seal) Acting Commissioner of Patents.

specifi cation

